Insulation is an essential part of industrial building and construction, especially in the chemical and petrochemical industry where physical and chemical reactions take place at very high temperatures and where transport and storage require extremely low temperatures, e.g. ranging from −40° C. for ammonia over −100° C. for ethylene down to −165° C. for liquefied natural gas or even down to −200° C. and less for liquefied air components. Down from −80° C. the industry usually is speaking of “cryogenic conditions”. The insulation of pipework, tanks etc. bearing such cryogenic conditions is extremely challenging due to the fact that all materials will get frozen in a certain manner, condensation of humidity from the air to ice is a real problem, and even materials being soft at 0° C. will become abrasive to the installation when talking about cryogenic temperatures. Sole material or single layers can not provide safe and sufficient insulation of cryogenic temperatures, therefore whole insulation systems are used, consisting of multiple layers of insulation material in its composites mostly covered by a cladding (as basically described in some documents filed by chemical companies, such as Linde: DE 19954150, Mitsubishi: GB 1438226, Exxon: GB 1110579, and Dow: GB 1447532).
In the past, mainly inorganic materials had been used for cryogenic insulation, namely mineral wool, glass fibre and foamed glass, or sometimes aerogels (e.g. U.S. 20080087870). The fibrous materials lack of resistance to water vapour transmission (WVT) and have to be installed in rather complex systems by taking absolute care to seal the installation completely, because else condensation of humidity to ice would occur through the insulation, leading to the notorious under insulation corrosion or to the insulation being first diminished and then destroyed by permanent ice layer growth. Foamed glass or aerogel insulation is also critical concerning the WVT, and additionally is very brittle and known for complicated mounting (in the case of aerogels also some health risks are discussed) and inevitable scrap.
It is often claimed as a major of advantage of inorganic systems that they are fire safe; this, however, is only true for the pure insulation material itself, because seals, seam protection, application of adhesives for joints, lamination etc. is essential for the application of these materials, and the products used for providing that are organic and therefore combustible. This is also true for a second class of cryogenic insulations being organic and based on polycondensate polymer foam, mainly polyurethane (PUR) or polyisocyanurate (PIR). These materials show acceptably low thermal conductivity (however, attention has to be paid to the fact that often thermal conductivity values are provided with the foaming gas still being present in the cells and not yet being replaced by air that would render the insulation performance worse), as well as acceptable WVT. Their brittleness is lower than for foamed glass and it is available in more shapes that even can be adapted on site within a small range. Polyolefin insulations (see e.g. EP 0891390, or JP 5208438, where an elastomeric foam hose protects an inner polyolefin layer) as an alternative to PUR/PIR are rare in the cryogenic field and show almost the same deficiencies.
Some work has been done on the improvement of thermoplastic materials and on the insulation systems using them, such as disclosed in DE 19954150GB 1438226, GB 1110579, GB 1447532, or EP 1878663, CN 2937735 and CN 101357979 (mentions LNG insulation), all based on PUR/PIR. GB 1436109 discloses an insulation material for cryogenic containers based on modified polyurethane; FR 2876438 describes the possible use of (expensive) polyether imide foam and GB 2362697 as well as U.S. Pat. No. 5,400,602 mention a complex and likely expensive PTFE based system for cryogenic fluid transfer; CA 1179463 claims improved rigid insulation sheet for cryogenic purposes obtained by compression of thermoplastic foam; CA 1244336 describes an improved multilayer system based on styrenic foam, whereas CN 1334193 claims a multilayer system based on PUR, foamed glass or expanded perlite, whereas U.S. Pat. No. 4,044,184 describes an insulation board coated with a plurality of rigid foam layers. All these systems require at least one, mostly several vapour barriers, and are very sensitive to mechanical impact, such as somebody stepping on an insulated part, or vibration.
Some examinations also have been carried out on thermoplastic elastomers (TPEs) or similar copolymers, such as in CN 101392063 (polysiloxane/polyamide) and WO 2001030914 (polyester/polyether/polyamide) or GB 1482222 (foamed polyethylene copolymer). However, at very low temperatures it is known that the TPEs' thermoplastic blocks will act as a crystallization initiator and overcompensate the properties of the elastomeric blocks, apart from the fact that all polymers bases used are not blocking vapour migration and thus will lead to a bad WVT performance, and their sensitivity to mechanic shock. CN 201060692 and CN 101221836 mention a (massive) elastomeric insulation layer for wind energy cables being exposed to low temperatures (−40° C. and lower), DE 19954150 mentions an elastomer as part of a cryogenic insulation system, however, as a massive and outer layer, too. DE 60114744 describes adhesives also for low temperatures based on ethylene-propylene terpolymers. Terpolymers in fact being of interest for low temperature applications are ethylene-propylene-diene polymers as base for elastomers (EPDM). EPDM has been mentioned in some cases to be able to withstand some low temperature impact: WO 2003002303 claims a nozzle made from massive EPDM (however, a very hard one) for treating surfaces with cryogenic particles; U.S. Pat. No. 4,426,494 describes an unsaturated ethylene polymer (a class where also EPDM can be found) and mentions improved properties for cryogenic area among others. However, detailed and extensive investigations about the cryogenic insulation properties of rubbers in general, especially expanded co- or terpolymeric rubber, such as EPDM foam, do not appear to have been done so far.